The studies proposed are directed toward acquiring further understanding of the immunochemical, biochemical, physicochemical, and genetic properties and of the functional significance of normal immunoglobulins through the study of homogeneous immunoglobulin components (Bence Jones proteins, myeloma proteins, Waldenstrom macroglobulins) found in patients with multiple myeloma and related hematologic disorders. These studies include: the establishment of concordance between immunochemical and structural features of human immunoglobulins, with emphasis on the utilization of immunochemical techniques to provide a rapid and sensitive means for detecting and localizing differences in the amino-terminal (variant) half of the light polypeptide chain of immunoglobulins: the characterization and significance of physical, chemical, immunochemical, genetic, and functional properties of structurally-defined, homogeneous immunoglobulin domains; and the study of the formation and functional significance of the homogeneous units, subunits, and fragments of immunoglobulins found in the serum or urine of patients with malignancies involving primarily the plasma cell-lymphatic system as well as those involving other organ systems.